Mother Monster tore the muscle that helps hold the hip joint, forcing her to cancel shows.

Tests revealed Wednesday that Lady Gaga tore her labrum -- a layer of muscle that helps hold the hip joint in place -- requiring her to undergo surgery and cancel the rest of her tour dates.

Little Monsters who had tickets for the 21 dates remaining in the Born This Way Ball tour will get a refund beginning Thursday.

Earlier, when the tour was merely postponed, Gaga revealed her injury to fans via a tweet.

"I've been hiding a show injury and chronic pain for sometime now, over the past month it has worsened," Gaga shared Tuesday afternoon. "I've been praying it would heal."

The injury is a synovitis, a severe inflammation of joints, she said, adding, "I hid it from my staff, I didn't want to disappoint my amazing fans. However after last night's performance I could not walk and still can't."

She went on to say, "To the fans in Chicago Detroit & Hamilton I hope you can forgive me, as it is nearly impossible for me to forgive myself. Im devasted & sad."